Here is the full list of all 20 Sundered: Eldritch Edition achievements worth 1,000 gamerscore.
Collect 500,000 Shards
Defeat Hysteria
Equip three Perks simultaneously
Unlock all Abilities
Corrupt your first Ability
Defeat Dominion
Collect 10,000 Shards
Equip your first Perk
Defeat you first Miniboss
Survive your first horde
Unlock your first Ability
Destroy your first Elder Shard
Destroy seven Elder Shards
Corrupt seven Abilities
Defeat all Minibosses
Find all Perks
Defeat Legion & Salvation
Defeat Nyarlathotep
Defeat Nyarlathotep & The Shining Trapezohedron
Defeat Humanity